1. Field of the Invention
The invention relates to the field of applicators for applying moisture-absorbent powder on cable elements and to the field of methods of applying moisture-absorbent powder on cable elements. This powder has the function, once the cable has been produced, of absorbing moisture lying in certain elements of the cable so as to prevent this moisture from degrading the properties of these cable elements and of preventing this moisture from propagating along these cable elements.
2. Description of the Prior Art
According to one prior art, it is known to make cable elements, such as optical fibers, or tubes containing optical fibers, pass through a cylinder approximately 600 mm in length connected to a reservoir of moisture-absorbent powder. The powder reservoir is located in the bottom part of the machine. The powder is then sucked up by a Venturi-suction system, the suction being achieved with filtered air and requiring pressure regulation in order to obtain a sufficient powder flow rate. The powder conveyed is then injected into the cylinder under adjustable pressure in order to obtain the necessary amount of powder on the cable elements. The powder is then deposited on the cable elements while they pass through the cylinder, by means of radial powder jets, which powder is conveyed by a compressed gas, such as compressed air, and is injected laterally onto the cable elements. Active means are needed to generate this compressed gas intended for conveying the powder. One drawback of this prior art is that, since the powder is conveyed by a pressurized gas, said powder is dispersed over a wide region in the vicinity of the applicator and of the cable in the process of being assembled. Consequently, there is a risk of other machines or apparatuses in the vicinity of the applicator being contaminated by the powder and having to be frequently stopped for cleaning, which is bothersome. Moreover, the presence of powder on the floor within a perimeter of several meters around the applicator incurs the risk of the operators, moving around near the applicator, falling over. Another drawback is that the flow rate of powder onto the cable elements is relatively irregular.
To solve, or at the very least reduce, all or some of these problems, the invention proposes a different applicator and a different method of application. Instead of conveying the powder by a pressurized gas, in order to inject it laterally, the invention is based on application by powder dropping vertically, with the use of a mechanical stirrer located in a hopper, the movement of the mechanical stirrer, which is a mechanical component whose movement in the hopper stirs the powder contained in the hopper, being sufficient to make the powder flow under gravity as far as the cable elements. The applicator according to the invention, operating under gravity, also has the merit of being simpler than that of the prior art, especially as regards its adjustment and its use. A minor drawback is that, during a stoppage of the applicator lasting several hours, it is necessary to ensure that the powder in the hopper of the applicator is replaced, as otherwise said powder would risk taking up moisture and forming crumbs.